Hello everyone. I've enjoyed all these threads with testing and failures and successes so I'm adding a bit of my own. I'm wandering down a path of some modifications for my cnc, and intend to do some plate cutting out of aluminum to accomplish the goals. Having never cut any metals with a cnc it was a little nerve wracking and has cost me a few small 1/8" end mills in the process but it's been a fun learning curve all the same. The good news for me (as many have shown) is that it is definitely possible, and after figuring a few things out the results seem to be pretty good even. After just a few days of trial and error my main takeaways are: most cuts are possible without misting and airblast setups. With the right, typically very shallow DOC you can maintain some fairly high feedrates, more than I initially thought at least. There's a big difference in chip clearing capability between the 1 and 2 flute bits There's a big difference in bit strength between the 1 and 2 flute bits... Trochoidal milling is magic! I used some general guides (fswizard) to approximate the feedrates and they helped but as we know with these machines it's never quite that easy. I had to be a lot more cautious generally but that was usually just on the DOC and WOC otherwise the feedrates were decent as long as I paid attention to the chips/tooth magic number of 0.001"/tooth which seemed to hold fairly true. I found in my initial and probably appropriate caution that my combination of very shallow plunge angles and slow z feedrates were adding a ton of time to my programs just getting the bit from the clearance heights down to the work surface. For me it was pick one to be cautious with and the other to care less about so I kept shallow plunge angles and increased my z feedrate which has sped things up while not introducing too much danger. I haven't used any cutting oil, or air blast, and the only place where this has presented real problems is in slot cutting. Recutting chips as all the guides suggest is a quick way to bit death. Doubly so for the 2 flute bits I tried. 2 flute bits produced much nicer finishes, and allowed for higher feedrates, and never snapped on me. However I chip welded 2 to death, and ended up realizing that the o-flute bits are a little easier if you're minding the cutting forces. First project I'm trying is to create a fixture plate, I'm hoping this provides some work holding options for smaller aluminum cutting down the road. So far for these plate type cuts, tape and glue has been excellent. Last thing is the trochoidal milling, I CAM in estlcam and the trochoidal milling option with a larger 1 flute 1/4" bit successfully got me all the way around about 1.3m of a contour cut in my 13mm aluminum plate in 3 passes (2 roughing/1finish) at 13.4mm. Cutting time was close to 90 minutes but it ran flawlessly, 6.7mm doc, feedrate of 3000mm/min, 90% stepover, 5% trochoidal oscillation, and 50% width of trochoidal loops so about a 9.5mm slot was cut all the way around. It made a huge pile of chips, but never hesitated. I'm thrilled. here's the testing ahead of the real thing: and here's the cut plate: and the mess So not really intending to teach anything here but just to share and encourage anyone who's been thinking about it to give it a try.
All done now with the cnc phase, it turned out well. Now I have hundreds of holes to tap. After a few surfacing runs it was already nearly perfectly flat, I needed 0.5mm to get the whole top scratched off.
None at all. I run the high torque steppers but I don't believe those are limiting factors at all as I don't think the frame's rigid enough to push hard enough for it to matter. For me as noted it was more about getting the feedrates and cutting strategies correct, as well as using those glorious 1 flute o-flute bits. There is still trial and error but these machines can do it with a healthy dose of patience and effort.
Well it comes and it goes quickly. I've continued to cut and had successes and failures along the way. Definitely get more leeway with a 1/4" bit compared to the little 1/8" bits. I'm working my way towards a linear rail setup for my gantry, and I've finally got the plate cut for the z, after some mis-measurements on my part. Conceptually I'm having a hard time knowing what I need for this even with people having completed this before. My main reason for the move is I seem to get a large amount of deflection from the z-axis wheels in plunging cuts and as I push the machine. Cutting aluminum has highlighted this especially in the plunging drilling operations which I know are tough for the machine. I purchased a cnc specific drill bit which made a big big difference for the 3mm holes I was drilling for the plate. After making that switch I got to the cnc accurate drilling that I had hoped for/expected. Anyways fun learning through all this stuff, and fortunately, 1/8" bit are relatively inexpensive so snapping one doesn't make me cry (too much!)
Not really meant to be a build thread by any means but here's the work I was getting towards, nearly all wrapped up. Fun to see it go together.
